Recently, an excavator, a bulldozer, or another working machine has been proposed such as one equipped with a global positioning system (GPS) or the like with which the working machine detects a position thereof for itself and compares that positional information with construction information indicating a landform of a construction site to obtain an attitude of a working instrument through computational processing such that the movement of the working instrument is controlled or a construction condition is displayed on a monitor device as a guidance by examining an attitude or a position of the working instrument relative to the construction information (refer to Patent Literature 1). Construction using such a working machine is referred to as computer-aided construction. By using the computer-aided construction, even an operator not skilled in operating the working machine can realize highly accurate construction. For a skilled operator, the computer-aided construction enables highly efficient construction. The computer-aided construction can considerably reduce surveying operation and finishing stake operation that have been required in the past.